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0002041: Link balancing (=combining multiple uplinks to the internet) - MantisBT Endian Bugtracker
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IDProjectCategoryView StatusDate SubmittedLast Update
0002041Endian FirewallNetwork related (VPN, uplinks)public2009-07-28 01:282010-09-24 09:21
Assigned Topeter-endian 
PlatformOSOS Version
Product Version2.2 
Target VersionFixed in Version 
Summary0002041: Link balancing (=combining multiple uplinks to the internet)
DescriptionIt would be great if the feature of being able to have multiple uplinks would be expanded towards the ability of COMBINING those uplinks.

This is called "LINK BALANCING". There are some hardware appliances out there in the market, which are VERY expensive (>3000€ for 3 uplinks).

This feature would give small-and-medium-sized enterprises (SMEs) the possibility in having a greater upload-speed by combining cheap DSL lines (e.g. here in Greece 20€/month for 24/1 Mb/s), instead of having to lease a line (e.g. here in Greece >1000€/month for 2/2 Mb/s).

Additional InformationExample of an hardware appliance for link balancing: [^]

Maybe some places to start of:
- [^]
TagsNo tags attached.
Attached Files

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-  Notes
tomakos (reporter)
2009-07-28 01:50
edited on: 2009-07-28 02:23

link balancing, load balancing, multiple uplinks, link aggregation, transparent, combine DSL, balance-rr, round-robin, round robin, active-backup, balance-xor, 802.3ad, balance-tlb, balance-alb, layer2, layer2+3, layer3+4, Ethernet trunk, NIC teaming, port channel, port teaming, port trunking, link bundling, EtherChannel, Multi-Link Trunking (MLT), NIC bonding, Network Fault Tolerance NFT, WAN, WAN uplink

tomakos (reporter)
2009-07-28 01:53

Please see also the closely related: [^] [^]
tomakos (reporter)
2009-07-28 11:01

I am not a master of this subject, but I have set up a server who's NICs are bonded and have read a little about bonding of internet links. So let me explain with the little of what I know about the subject:

There is a difference when speaking about combining some LAN-NICs and WAN-NICs (=uplinks to the internet).

When bonding LAN-NICs,
e.g. with one of the existing modes called 802.3ad (AKA "Link Aggregation"), those bonded NICs recieve 1 IP. The switch to which those NICs are connected needs be a manageable switch and to support this protocol. You go into the settings of the switch and tell him: "Those NICs are bonded, so please treat them as one and don't be confused about that 1 IP and scrambled traffic." The switch then handles the traffic appropriately.

There are 7 different modes and 3 different hash-policies.. The ultimate mode is balanced-rr, which truely spreads all traffic on the NICs, down to the packet level. It's comparable with a RAID0 on those NICs.. Even a single file that you send will be spread over the multiple NICs.. I have not managed this, since my switch doesn't seem to support it. And secondly there is a lot of loss, since the packets are scrambled so much, that a lot of packages get dropped because of timeouts.. The next best choice is 802.3ad with hash-policy "layer3+4". This means, that the kernel will analyse traffic based on the IP and the protocol used. With this way at least, the kernel will try to span traffic to the same IP over different NICs according to the protocol used. E.g. FTP traffic towards IP1 via NIC1 and SIP-Telephony-Traffic towards IP1 via NIC2.

When bonding Internet Uplinks,
AKA "Link balancing", there is one problem that makes it impossible to use the same bonding techniques as with the LAN NICs: You can't influence the other side, that what would be the switch in you LAN: The internet providers!

So the balance-rr and 802.3ad modes are out of the game for sure.
But there are other modes of bonding, that may be of interest for further researching:

511 balance-tlb or 5
513 Adaptive transmit load balancing: channel bonding that
514 does not require any special switch support. The
515 outgoing traffic is distributed according to the
516 current load (computed relative to the speed) on each
517 slave. Incoming traffic is received by the current
518 slave. If the receiving slave fails, another slave
519 takes over the MAC address of the failed receiving
520 slave.


527 balance-alb or 6
529 Adaptive load balancing: includes balance-tlb plus
530 receive load balancing (rlb) for IPV4 traffic, and
531 does not require any special switch support. The
532 receive load balancing is achieved by ARP negotiation.
533 The bonding driver intercepts the ARP Replies sent by
534 the local system on their way out and overwrites the
535 source hardware address with the unique hardware
536 address of one of the slaves in the bond such that
537 different peers use different hardware addresses for
538 the server.
540 Receive traffic from connections created by the server
541 is also balanced.

I don't know if those modes of bonding are really usable for internet-uplink-bonding. I have found some other approaches in the internet:
- Changing the routing tables
- Making DNS-Round-Robins

I hope those information is somewhat helpful!

Best regards,

P.S. Those lines are taken of the "bonding.txt" THE source of information for setting up a NIC bond: [^] [^]
You will find all needed information about the modes and hash policies there!

- Issue History
Date Modified Username Field Change
2009-07-28 01:28 tomakos New Issue
2009-07-28 01:28 tomakos Assigned To => peter-endian
2009-07-28 01:50 tomakos Note Added: 0002795
2009-07-28 01:53 tomakos Note Added: 0002798
2009-07-28 01:56 tomakos Note Edited: 0002795
2009-07-28 02:00 tomakos Note Edited: 0002795
2009-07-28 02:23 tomakos Note Edited: 0002795
2009-07-28 11:01 tomakos Note Added: 0002806
2010-09-24 09:21 peter-endian Status new => closed
2010-09-24 09:21 peter-endian Resolution open => duplicate

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